This invention relates to a method for detecting the rate of polymerization. More specifically, it relates to such a polymerization rate detection method which is best suited for detecting the polymerization rate of a polymer composition in a polymerization reaction process using any kind of polymerization such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc.
In a polymerization reaction process of a polymer composition, it is important for proper quality control of the composition to detect the polymerization rate of the polymer composition in the course of the polymerization reaction process in a short time and with high accuracy.
Heretofore, the polymerization rate of a polymer composition in a polymerization reaction process has been detected by applying an interrelation existing between polymerization rate and viscosity of polymer composition under certain constant conditions (such as measuring temperature, polymerization temperature, shear rate in measurement of viscosity, etc.). In such a conventional method, the viscosity of the polymer composition to be examined is first measured and the polymerization rate of the polymer composition is detected from a diagram representing the polymerization rate-viscosity relation of polymer compositions which diagram has been obtained from the experimentally obtained data.
Such a detection method, though capable of detecting the polymerization rate of a polymer composition in a polymerization reaction process in a short time, had the following disadvantages.
(1) As it is generally difficult to keep constant such conditions as measuring temperature and shear rate in measurement of viscosity of polymer composition, errors tend to appear in determination of polymerization rate of polymer composition from the polymerization rate-viscosity diagram on the basis of the measured viscosity. This makes impossible high-accuracy detection of the polymerization rate of the polymer composition in a polymerization reaction process, disenabling proper quality control of the polymer composition throughout the reaction process.
(2) A change in any of the conditions such as measuring temperature, polymerization temperature, shear rate in measurement of viscosity, etc., causes a corresponding change in the relation between polymerization rate and viscosity of polymer composition. Therefore, when drawing up a polymerization rate-viscosity diagram with such possible changes in mind, a vast accumulation of data on the relation between polymerization rate and viscosity of polymer compositions changeful with diversified combinations of said variable conditions is necessitated, for which a great deal of time and expense are required.
An analytical method by use of a gas analyzer (gas chromatography) is known for detecting the polymerization rate of a polymer composition with higher accuracy. This method, however, is rather complicated in its process, which essentially comprises a sample dissolving step in which a sample of the polymer composition to be analyzed is dissolved in a solvent to form a sample solution, a sample solution measuring step in which a small amount of said sample solution is quantified accurately and supplied into the analyzer, and an analysis step where the sample solution in the analyzer is gasified and passed through a filler-packed column and the efflux rate at the column outlet is measured and output as a calibration curve. The objective polymerization rate is detected by passing these steps, so that this method is incapable of short-time detection of the polymerization rate of a polymer composition in a polymerization reaction process and is therefore unable to ensure proper quality control of the polymer composition throughout the reaction process.